全方位治理城市交通,促进城市可持续发展

城市交通对城市的社会经济活动和生态资源环境具有双向作用,是城市功能中最活跃的因素.目前城市交通问题突出表现在交通阻塞和汽车尾气污染两个方面,已成为困扰着大中城市发展的主要问题.交通堵塞不仅给人们的生活和工作带来不便,而且增加了城市经济运行的时间成本,影响到城市功能的发挥和城市的健康发展,同时又进一步加剧了能源的消耗.可见城市交通问题是关系到城市可持续发展的关键问题之一.     

Towards a generalized TLM algorithm for solving arbitraryreciprocal and nonreciprocal planar structures

A generalized transmission line matrix (TLM) algorithm is developed in the frequency domain to tackle arbitrary both reciprocal and nonreciprocal anisotropic waveguiding problems. In particular, the modeling issue for arbitrary planar structures is stressed in this work. A new three-dimensional (3-D) condensed node is used to consider the effect of both electric and magnetic constitutive tensors. Various results indicate how the modal dispersive behavior can be manipulated by changing not only the anisotropic characteristics of the substrate, but also the strip/slot geometry as well as the magnitude and orientation of the applied static magnetic field. The present algorithm is useful for CAD and simulation of a large class of gyrotropic waveguide-based microwave and millimeter-wave circuits     

An analytical grain-barrier height model and its characterizationfor intrinsic poly-Si thin-film transistor

An analytical model for the grain-barrier height of the intrinsic poly-Si thin-film transistors (TFTs) is developed, in which the grain-barrier height for the applied gate voltage smaller than the threshold voltage is obtained by solving the charge neutrality equation and the grain-barrier height for the applied gate voltage larger than the threshold voltage is obtained by using the quasi-two-dimensional (2-D) method. Good agreements between experimental and simulation results are obtained for a wide gate voltage range     

A microprocessor-based toggle-control lighting system

Analysis, design, practical consideration, and implementation of a microprocessor-based toggle-control lighting system are presented. The system is primarily configured with a power factor corrector (PFC), a square-wave voltage generator, a manually controlled toggle switch, and two relays. Toggling the toggle switch can select a different number of lamps in operation, resulting in a mutual dimming feature. A fluorescent lamp lighting system with this specific ballast gains the merits of lower system cost and more flexibilities in lighting fixture design, as compared to conventional systems     

Transdermal Iontophoretic Delivery of Thyrotropin-Releasing Hormone Across Excised Rabbit Pinna Skin

Enhanced transport of a model peptide drug thyrotropin-releasing hormone (TRH), a tripeptide of molar mass 362 g and a pK_a 6.2, through excised rabbit pinna skin was achieved by means of iontophoresis with continuous current or monophase periodically pulsed current. The resulting flux in the steady state was proportional to the applied current density. In the transdermal iontophoretic delivery of TRH, the pulsed iontophoretic flux exceeded that obtained with a continuous current. At a low ionic strength, an increased degree of protonation in TRH increased the rate of permeation. The flux of TRH in a buffer at pH 4 is greater than that at pH 8 when the ionic strength is 0.1 M. At a greater ionic strength, the trend is reversed. The enhanced flux of unprotonated TRH during transdermal iontophoresis is attributed largely to electro-osmotic volume flow. An increased rate of permeation of TRH crossing the skin is achieved at low ionic strength, moderate pH, and a large duly cycle of current; the frequency of pulsed current had no significant influence on the rate of transdermal iontophoretic delivery of TRH.     

The As-prepared surfaces of C-axis-oriented Nd1Ba2Cu3Oy thin films characterized using scanning probe microscopes

Recently, superconducting Nd₁Ba₂Cu₃O_y (Ndl23) thin films with high superconducting transition temperature (T _c) have been successfully fabricated at our institute employing the standard laser ablation method. In this paper, we report the results of surface characterization of the Nd123 thin films using an ultrahigh vacuum scanning tunneling microscope/spectroscopy (UHV-STM/STS) and an atomic force microscope (AFM) system operated in air. Clear spiral pattern is observed on the surfaces of Nd123 thin films by STM and AFM, suggesting that films are formed by two-dimensional island growth mode. Contour plots of the spirals show that the step heights of the spirals are not always the integer or half-integer number of thec-axis parameter of the structure. This implies that the surface natural termination layer of the films may not be unique. This result is supported byI-V STS measurements. The surface morphology of the Nd123 thin films is compared with that of thec-axis-oriented Y₁Ba₂Cu₃S_y thin films. Surface atomic images of the as-prepared Nd123 thin films are obtained employing both STM and AFM. STS measurements show that most of the surfaces are semiconductive. The results of STS measurements together with the fact that we are able to see the surface atomic images using scanning probe microscopes suggest that exposure to air does not cause serious degradation to the as-prepared surfaces of Nd123 thin films.     

三相异步电动机运行指标的分析

利用电机学理论分析了影响电机起动转矩、起动电流、最大转矩和最小转矩的因素。     

Review of Daqing＇s Technologies in 10th Five-Year Plan Period

During the 10^th Five-Year Plan Period, Daqing Oil Field entered the late high water-cut period with the reserve production ratio in imbalance. The oil field development became more and more difficult owing to the inadequate substitute resources. Daqing Oil Field Company has made a series of important and new technological achievements to solve those bottlenecks. The oil field has cumulatively achieved a total of technological results, of which eight items are at the State level, 96 items at the provincial and ministerial level, and 1009 items granted with the patent rights. The oil field has developed a family of exploration and development technologies which are world-leading and self-developed with an independent IPR.     

In situ polymerization and characterization of polyester‐based polyurethane/nano‐silica composites

Polyester‐based polyurethane/nano‐silica composites were obtained via in situ polymerization and investigated by Fourier‐transform infrared spectroscopy (FTIR), or FTIR coupled with attenuated total reflectance (FTIR‐ATR), Transmission electron microscopy (TEM), atomic force microscopy (AFM), an Instron testing machine, dynamic mechanical analysis (DMA) and ultraviolet‐visible spectrophotometry (UV‐vis). FTIR analysis showed that in situ polymerization provoked some chemical reactions between polyester molecules and nano‐silica particles. FTIR‐ATR, TEM and AFM analyses showed that both surface and interface contained nano‐silica particles. Instron testing and DMA data showed that introducing nano‐silica particles into polyurethane enhanced the hardness, glass temperature and adhesion strength of polyurethane to the substrate, but also increased the resin viscosity. UV‐vis spectrophotometry showed that nano‐silica obtained by the fumed method did not shield UV radiation in polyurethane films. Copyright © 2003 Society of Chemical Industry